Synthesis of new water treatment photocatalytic coatings with controllable functional properties based on the SrO-Bi2O3-SiO2 system that use the energy of solar radiation

Abstract

This work is devoted to the study of water purification from organic pollutants using new environmentally safe photocatalysts capable of using solar insolation to oxidize organic pollutants. Most methods of creating photocatalysts allow obtaining them only in powder form, which limits their application in water treatment plants. In this regard, photocatalysts formed as coatings on the carrier surface may be more promising. This work contributes to solving the problem of developing a technologically concise and economical method of creating bismuth photocatalytic coatings with biological indifference and high light absorption efficiency (LAE) of solar irradiation. The developed cleaning material is a structurally organized system consisting of a ceramic carrier on which a photocatalytic coating is formed. The coating was formed by soaking the silicate carrier in a bismuth precursor solution (BPS) followed by drying and oxidative pyrolysis. The highest catalytic activity and LAE (58.3–60.3%) were observed for the materials obtained at 10–15% wt. bismuth in BPS. The highest hydrolytic stability was observed at 25% wt. bismuth in BPS. Strontium bismuthate SrBi7.65O13 was the dominant phase in the coating composition for the samples with the highest activity and LAE. Increasing the content of another photocatalytically active phase Bi4Si3O12 resulted in the LAE decreasing to 51.9%, providing greater hydrolytic stability of the material. The proposed method allows for flexibly controlling the properties of the obtained photocatalytic coatings, thus making possible to directionally create different types of materials to be applied in the field of wastewater treatment.